There are known several communication methods designed for wireless communication between mobile stations.
Time division multiple access (TDMA) is a channel access method for shared medium networks. It allows several radio stations to share the same frequency channel by dividing the signal into different time slots. The stations transmit in rapid succession, one after the other, each using its own time slot.
There are known time divided duplex radio communication systems, which utilize time slots of equal duration, wherein one data packet is sent per each time slot. This can be inefficient in case the data packet is shorter than the transmission capacity of the time slot.
GSM (Global System for Mobile Communications) is an example of a well-known cellular telephony system, wherein a plurality of mobile stations (cell phones) communicate with each other via a base station. Individual TDMA channels are formed between the mobile station and each base station. A packet of data to be transmitted from a first mobile station to a second mobile station is first sent from the first station to the base station via a first channel (upstream/uplink) and then forwarded by the base station to the second mobile station via a second channel (downstream/downlink). Therefore, to enable communication between mobile stations in a particular region, a base station shall be installed that has a communication range covering that region. Therefore, an infrastructure of base stations has to be created to enable communication.
A U.S. Pat. No. 5,481,539 discloses a radio communication TDMA system comprising a plurality of mobile units. The mobile units receive packets transmitted by other units and repeat these packets to other units in a time slot other than the time slot assigned to that mobile unit.
A PCT patent application WO2011035440 discloses a method of facilitating radio communications that involves receiving and transmitting messages on a plurality of channels using various radio technologies, such as TDMA or CDMA. WO2011035440 does not relate to organization of packets within a single time slot of a TDMA system.
There are situations, when communication over a plurality of mobile stations must be provided in an environment without a pre-installed infrastructure of base stations. Moreover, there are environments wherein installation of base stations would be problematic. Examples of such environments include open environments such as large unpopulated areas (e.g. deserts), or limited environments such as underground mines or caves.
Transmission of signal in long, narrow and curved tunnels, such as adits in an underground mine, may require use of repeaters in order to transmit the signal from one end to another end of the tunnel. A radio repeater is a radio receiver and transmitter that retransmits a radio signal to extend the range of coverage of the radio signal. Various types of repeaters can be utilized for this purpose, including repeaters configured for open-space networks. However, the known radio repeater systems typically require considerable power resources to operate, both at the repeater and the communicating stations. This can be particularly troublesome in harsh environments, such as underground mines, wherein the equipment should be easy to install and should utilize low power to operate, e.g. to be battery-operated for a long time.
There is therefore a need to provide a simple radio communication system which can solve at least some of the problems associated with the known systems, such as: communication over an open environment, communication over a limited environment, communication over a long, narrow and curved tunnel, a need to provide a pre-installed infrastructure of base stations or repeaters, bandwidth required for data transmission, power required for data transmission, simultaneous transmission of signal between multiple stations.